So, if you are a business, I think relying solely on AWS is a super bad idea. Amazon is aware of the lock in effect, and if your usage spikes and you don't have a good alternative ready to go? Amazon is setup so that you will pay through the nose. AWS is wonderfully cheap if you only need a little bit, but it is crushingly expensive at any kind of real scale.

Starting on amazon is great, as it really is cheap at small scale, and you can test your shit at large scale for short periods... but it gets expensive fast as you grow, so the more you can do to prepare to move, (or credibly threaten to do same) the better off you are.